Conventionally, a wireless communication system operates in a proprietary radio frequency (RF) spectrum in which base stations and wireless terminals communicate through the proprietary RF spectrum licensed to a wireless operator. However, there have been discussions of wireless communication systems expanding usages to unlicensed spectrum, such as the Industrial, Scientific and Medical RF spectrum (ISM band) or other free spectrum. The possibilities of Long Term Evolution (LTE) or LTE-advanced communication systems entering the domain of the unlicensed spectrums have drawn attention for telecommunication equipment vendors and operators. One reason for such interest is the potential overcrowding of licensed spectrums. In order to provide high throughput services to more users, incursions into unlicensed spectrums might deliver benefits for wireless communication systems.
In 2014 September, a new study item, namely “Study on Licensed-Assisted Access using LTE” was approved for investigations related to 3GPP Release 13. The framework for Licensed-Assisted Access (LAA) to unlicensed spectrum has also been known as Unlicensed LTE (LTE-U), which may potentially be a key feature for the next generation cellular system.
One of the challenges of a wireless communication system operating in unlicensed spectrum is to operate within an environment of uncertainty under which devices belonging to the wireless communication system have to co-exist with devices that are not controlled by the wireless communication system. For example, assuming that a LTE communication system conducts a wireless communication in an unlicensed or shared spectrum, there might be other communications devices, either using the same radio access technology or different radio access technologies, which would like to also share the same unlicensed spectrum. The sharing of unlicensed spectrum might cause mutual interferences or contentions. At this point in time, it would be highly conceivable that LTE operations that transpire in unlicensed spectrum would need to cope with problems related to the operation of Wi-Fi radios within the same unlicensed spectrum.
Therefore, a method and related device that provides an adequate solution for sharing radio resources in an unlicensed spectrum might be required.